2010 Mercedes-Benz E-Class battery wont charge

My Battery won’t charge, both the alternator and battery have been checked and are fine. When I get the car started the engine revs up and down while in park and the traction control shows that it is turned off.

If the battery won’t charge, something is either wrong with the battery or the alternator or the car’s charging scheme. Since the first two have been eliminated, it must be the car’s charging scheme. Newer cars tend to use the computer for the charging algorithm. If the AC is on and you are in stop and go driving it may wait to charge the battery, for concerns the engine may stall at stoplights. There may be some sensor (AC switch or VSS for example) that’s not working correctly, and is confusing the computer.